Inter-sexual differences in resting metabolic rates in the Texas tarantula, Aphonopelma anax

Shillington, Cara

doi:10.1016/j.cbpa.2005.09.010

Cited by 44 publications

(51 citation statements)

References 38 publications

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“…weight exponent of standard metabolism) were higher in males than in females (e.g. Shillington 2005), total metabolic costs of males in this study might be underestimated. Another possibility is that females are experiencing compensatory growth as a response to more variable intake relative to males.…”

Section: Discussioncontrasting

confidence: 55%

“…1977), and potential gender differences in these submodels have not been evaluated. Although published accounts show that standard metabolism and assimilation efficiencies can differ between males and females (Shillington 2005; Valle et al . 2005), sufficient data are currently lacking to parameterize accurately gender‐based submodels for consumption and metabolism in percids.…”

Section: Discussionmentioning

confidence: 99%

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Lazy males? Bioenergetic differences in energy acquisition and metabolism help to explain sexual size dimorphism in percids

Rennie

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Lester

et al. 2008

Journal of Animal Ecology

100

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Summary1. Differences in energy use between genders is a probable mechanism underlying sexual size dimorphism (SSD), but testing this hypothesis in the field has proven difficult. We evaluated this mechanism as an explanation for SSD in two North American percid species -walleye Sander vitreus and yellow perch Perca flavescens . 2. Data from 47 walleye and 67 yellow perch populations indicated that SSD is associated with the onset of maturation: typically, males of both species matured smaller and earlier and attained a smaller asymptotic size than females. Males also demonstrated equal (perch) or longer (walleye) reproductive life spans compared with females. 3. To examine whether reduced post-maturation growth in males was due to lower energy acquisition or higher reproductive costs we applied a contaminant mass-balance model combined with a bioenergetics model to estimate metabolic costs and food consumption of each sex. Mature males exhibited lower food consumption, metabolic costs and food conversion efficiencies compared with females. 4. We propose that slower growth in males at the onset of maturity is a result of decreased feeding activity to reduce predation risk. Our finding that SSD in percids is associated with the onset of maturity is supported by laboratory-based observations reported elsewhere, showing that changes in growth rate, consumption and food conversion efficiency were elicited by oestrogen (positive effects) or androgen (negative effects) exposure in P. flavescens and P. fluviatilis . 5. Researchers applying bioenergetic models for comparative studies across populations should use caution in applying bioenergetic models in the absence of information on population sex ratio and potential differences between the sexes in energetic parameters.

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Section: Discussioncontrasting

confidence: 55%

Section: Discussionmentioning

confidence: 99%

Lazy males? Bioenergetic differences in energy acquisition and metabolism help to explain sexual size dimorphism in percids

Rennie

Purchase

Lester

et al. 2008

Journal of Animal Ecology

100

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“…Most arachnids exhibit this typical temperature-dependent pattern for locomotion (Prestwich, 1983;Shillington, 2005;Kruse et al, 2008;Carlson and Rowe, 2009;Wu et al, 2010). However, hunting ability in crab spiders remains constant across temperatures (Schmalhofer and Casey, 1999).…”

Section: Introductionmentioning

confidence: 98%

Effect of temperature on leg kinematics in sprinting tarantulas (Aphonopelma hentzi): high speed may limit hydraulic joint actuation

Booster

Adolph

et al. 2015

Journal of Experimental Biology

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Tarantulas extend the femur-patella ( proximal) and tibia-metatarsal (distal) joints of their legs hydraulically. Because these two hydraulically actuated joints are positioned in series, hemolymph flow within each leg is expected to mechanically couple the movement of the joints. In the current study, we tested two hypotheses: (1) at lower temperatures, movement of the two in-series hydraulic joints within a leg will be less coupled because of increased hemolymph viscosity slowing hemolymph flow; and (2) at higher temperatures, movement of the two in-series hydraulic joints will be less coupled because the higher stride frequencies limit the time available for hemolymph flow. We elicited maximal running speeds at four ecologically relevant temperatures (15, 24, 31 and 40°C) in Texas Brown tarantulas (Aphonopelma hentzi). The spiders increased sprint speed 2.5-fold over the temperature range by changing their stride frequency but not stride length. The coefficient of determination for linear regression (R 2 ) of the proximal and distal joint angles was used as the measure of the degree of coupling between the two joints. This coupling coefficient between the proximal and distal joint angles, for both forelegs and hindlegs, was significantly lowest at the highest temperature at which the animals ran the fastest with the highest stride frequencies. The coordination of multiple, in-series hydraulically actuated joints may be limited by operating speed.

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“…Individuals of similar body mass ( M b ) typically show 1·5‐ to 3‐fold differences in SMR and MMR within a single population (McCarthy ; Rogowitz & Chappell ; Nespolo, Lardies & Bozinovic ; Shillington ; Lardies et al . ; Gaitán‐Espitia et al .…”

Section: Introductionmentioning

confidence: 99%

Individual (co)variation in thermal reaction norms of standard and maximal metabolic rates in wild‐caught slimy salamanders

2014

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Summary1. Standard metabolic rate (SMR) and maximal metabolic rate (MMR) are fundamental measures in ecology and evolution because they set the scope within which animals can perform activities that directly affect fitness. In ectotherms, both SMR and MMR are repeatable over time when measured at a single ambient temperature (T a ). 2. Many ectotherms encounter variable T a from day to day and over their lifetime, yet it is currently unknown whether individual differences hold across an ecologically relevant range of T a (i.e. thermal repeatability; R T ). Moreover, it is possible that thermal sensitivity of SMR and MMR are important individual attributes, and correlated with one another, but virtually nothing is known about this at present. 3. We measured SMR and MMR across an ecologically relevant T a gradient (i.e. from 10 to 25°C) in wild-caught salamanders (Plethodon albagula) and found that R T was significant in both traits. SMR and MMR were also positively correlated, resulting in a lower R T in absolute and factorial aerobic scopes (AAS and FAS). 4. We found significant individual differences in thermal sensitivity for both SMR and MMR, but not for AAS and FAS. The intercept (at T a = 0°C) and the slope of the thermal reaction norms were negatively correlated; individuals with low MR at low T a had a higher thermal sensitivity. Finally, individuals with a high thermal sensitivity for SMR also had high thermal sensitivity for MMR. 5. Our results suggest that natural selection occurring over variable T a may efficiently target the overall level of -and thermal sensitivity in -SMR and MMR. However, this may not be the case for metabolic scopes, as the positive correlation between SMR and MMR, in addition to their combined changes in response to T a , yielded little individual variation in AAS and FAS. 6. Our results support the idea that organisms with low metabolism at low T a have a high metabolic thermal sensitivity as a compensatory mechanism to benefit in periods of warmer environmental conditions. Hence, our study reveals the importance of considering within-individual variation in metabolism, as it may represent additional sources of adaptive (co)variation.

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Inter-sexual differences in resting metabolic rates in the Texas tarantula, Aphonopelma anax

Cited by 44 publications

References 38 publications

Lazy males? Bioenergetic differences in energy acquisition and metabolism help to explain sexual size dimorphism in percids

Lazy males? Bioenergetic differences in energy acquisition and metabolism help to explain sexual size dimorphism in percids

Effect of temperature on leg kinematics in sprinting tarantulas (Aphonopelma hentzi): high speed may limit hydraulic joint actuation

Individual (co)variation in thermal reaction norms of standard and maximal metabolic rates in wild‐caught slimy salamanders

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